Copending U.S. patent application Ser. No. 881,043 filed Feb. 24, 1978 (which corresponds to German Offenlegungsschrift P 27 12 325) describes an optical display element in the form of a preferably plate-like body (fluorescent body) which is made of a material having an index of refraction of greater than one, contains fluorescent particles, has an at least partially reflective surface and bears a character, symbol or the like which optically contrasts with the background, and which is formed by appropriately shaped output coupling zones ("light outlet windows") of the fluorescent body.
In a very simple structure, a display of this kind provides a contrast which is uniformly high and is independent of environment, can easily be read even from oblique directions, and, if an additional illumination source is provided, consumes only a small quantity of power.